On /shop, when a snippet block sits above the searchbar, the search dropdown was rendered partially hidden behind that block (cropped/unreadable items).

Steps to reproduce:
===================
1. Go to /shop.
2. Add a snippet block above the searchbar.
3. Type in the searchbar.

=> Observed: search results appear cropped, with upper items
   hidden behind the snippet block above.

Root cause:
===========
the products grid column (`#products_grid`) has `overflow: auto`, https://github.com/odoo/odoo/blob/d9bb1c1dc90f97b63b87ad762fc4ab36abf7e05f/addons/website_sale/static/src/scss/website_sale.scss#L442 which clips any absolutely-positioned descendant
that extends past its bounds. The dropdown's containing block is the searchbar `<form>` (position: relative), which lives inside that column. When the dropdown grew (or flipped to dropup) and extended outside the column, the part outside was clipped, and any positioned snippet siblings above the column painted over the clipped area.

Fix:
======
while the dropdown is mounted, lift the `overflow: auto` on its ancestor `div.col` so the menu can extend past the column and paint on top of other content. Done from JS so no SCSS rule has to target the searchbar-specific column.

opw-6216317

---
I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

Forward-Port-Of: odoo/odoo#265982
Forward-Port-Of: odoo/odoo#265558